The present invention relates to a linking device including at least two shafts intended for the reciprocal articulation of two elements, and allowing filtering of vibrations between the two shafts.
The proposed linking device is intended in particular for aircraft engine attachments.
This device is intended, for example, to form a connecting rod, or a three-point shackle, or again a spreader beam for transferring thrust forces, to connect a turbine engine to a pylon, also called an EMS (Engine Mounting System). Generally speaking, such a pylon allows an engine to be suspended beneath the wing surface of an aircraft, or allows this engine to be mounted above this same wing surface or, again, allows this engine to be mounted on an aft portion of an aircraft's fuselage.
The proposed linking device is not limited to an application in the aeronautics field, and may be used for connecting two elements in any other type of application.
The invention also relates to a propulsion system for an aircraft including at least one linking device of this type, together with an aircraft fitted with at least one such propulsion system.
Airplanes' turbine engines are habitually attached to the wing surface or fuselage by means of a pylon to which the turbine engine is connected through engine attachments and thrust force transfer connecting rods.
FIG. 1 illustrates an example of a propulsion system 8, of the type intended to be attached laterally to an aft portion of an airplane fuselage. This propulsion system 8 includes a turbine engine 10, for example of the type having an unshrouded fan positioned at the aft, commonly called an open rotor pusher, and a pylon 12, which is partially visible, to which the turbine engine is connected. The fans, the nacelle and the air inlet of turbine engine 10 are not represented in FIG. 1, such that only the main structural casings of the turbine engine may be seen. Turbine engine 10 has a longitudinal shaft 11.
Turbine engine 10 is attached to pylon 12 mainly by a forward engine attachment 14, an aft engine attachment 16, and two thrust force transfer connecting rods 18, only one of which may be seen in FIG. 1.
FIG. 2 illustrates forward engine attachment 14 at a larger scale, together with the connection of connecting rods 18 to a rigid structure of pylon 12.
Forward engine attachment 14 includes a bracket 20 attached to pylon 12, to which a connecting rod 22 and a three-point shackle 24, also called a boomerang shackle, are connected. Connecting rod 22 is connected to bracket 20 by means of a first shaft, and is intended to he connected to turbine engine 10 by means of a second shaft. Shackle 24 is connected to bracket 20 by means of two shafts, and is intended to be connected to turbine engine 10 by means of a third shaft. The shafts of connecting rod 22 and of shackle 24 extend in parallel to longitudinal shaft 11 of the turbine engine which may be seen in FIG. 1. Finally, each of thrust force transfer connecting rods 18 is connected to a spreader beam 26, which is itself connected to bracket 20 by means of two shafts. It should be noted that the shafts of the elements described above are not represented in FIG. 2 for reasons of clarity.
However, connecting turbine engine 10 to pylon 20 by means of the elements described above causes vibrations of the turbine engine to be transferred to pylon 12.
This is particularly disadvantageous in the case of propulsion systems attached to the fuselage, as described above, since the vibrations are in that case transmitted directly to the structure of the airplane's fuselage. These vibrations are thus likely to increase wear and tear of the structure of the fuselage, and to impair the passengers' comfort.
Propulsion systems attached above or beneath the wing surface of airplanes generally include an engine attachments and thrust force transfer connecting rods configuration which is comparable to the one described above.
In these latter propulsion systems the vibrations caused by the turbine engines are in theory damped by the flexibility of the wing surface.
However, when the intensity of these vibrations is particularly high, notably in the event of a turbine engine operating incident, the vibrations of this turbine engine may also be transmitted to the structure of the airplane's fuselage.